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Determinants of maximal cycling power: Crank length, pedaling rate and pedal speed

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The purpose of this investigation was to determine the effects of cycle crank length on maximum cycling power, optimal pedaling rate, and optimal pedal speed, and to determine the optimal crank length to leg length ratio for maximal power production. Trained cyclists (n = 16) performed maximal inertial load cycle ergometry using crank lengths of 120, 145, 170, 195, and 220 mm. Maximum power ranged from a low of 1149 (20) W for the 220-mm cranks to a high of 1194 (21) W for the 145-mm cranks. Power produced with the 145- and 170-mm cranks was significantly (P < 0.05) greater than that produced with the 120- and 220-mm cranks. The optimal pedaling rate decreased significantly with increasing crank length, from 136 rpm for the 120-mm cranks to 110 rpm for the 220-mm cranks. Conversely, optimal pedal speed increased significantly with increasing crank length, from 1.71 m/s for the 120-mm cranks to 2.53 m/s for the 220-mm cranks. The crank length to leg length and crank length to tibia length ratios accounted for 20.5% and 21.1% of the variability in maximum power, respectively. The optimal crank length was 20% of leg length or 41% of tibia length. These data suggest that pedal speed (which constrains muscle shortening velocity) and pedaling rate (which affects muscle excitation state) exert distinct effects that influence muscular power during cycling. Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults.
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ORIGINAL ARTICLE
J.C. Martin áW.W. Spirduso
Determinants of maximal cycling power: crank length,
pedaling rate and pedal speed
Accepted: 15 January 2001 / Published online: 15 March 2001
ÓSpringer-Verlag 2001
Abstract The purpose of this investigation was to de-
termine the eects of cycle crank length on maximum
cycling power, optimal pedaling rate, and optimal pedal
speed, and to determine the optimal crank length to leg
length ratio for maximal power production. Trained
cyclists (n=16) performed maximal inertial load cycle
ergometry using crank lengths of 120, 145, 170, 195, and
220 mm. Maximum power ranged from a low of 1149
(20) W for the 220-mm cranks to a high of 1194 (21) W
for the 145-mm cranks. Power produced with the 145-
and 170-mm cranks was signi®cantly (P<0.05) greater
than that produced with the 120- and 220-mm cranks.
The optimal pedaling rate decreased signi®cantly with
increasing crank length, from 136 rpm for the 120-mm
cranks to 110 rpm for the 220-mm cranks. Conversely,
optimal pedal speed increased signi®cantly with in-
creasing crank length, from 1.71 m/s for the 120-mm
cranks to 2.53 m/s for the 220-mm cranks. The crank
length to leg length and crank length to tibia length
ratios accounted for 20.5% and 21.1% of the variability
in maximum power, respectively. The optimal crank
length was 20% of leg length or 41% of tibia length.
These data suggest that pedal speed (which constrains
muscle shortening velocity) and pedaling rate (which
aects muscle excitation state) exert distinct eects that
in¯uence muscular power during cycling. Even though
maximum cycling power was signi®cantly aected by
crank length, use of the standard 170-mm length cranks
should not substantially compromise maximum power
in most adults.
Keywords Skeletal muscle áExercise test á
Cycling power áCrank length
Introduction
Previous investigators have reported that maximal
cycling power is aected by cycle crank length (Inbar
et al. 1983; Too and Landwer 2000; Yoshihuku and
Herzog 1990, 1996) and that the optimal crank length is
related to leg length (Inbar et al. 1983). Inbar et al.
(1983) reported that peak cycling power for the Wingate
anaerobic test varied by 8% for crank lengths of 125±
225 mm. Since Inbar et al. (1983) reported their ®ndings,
it has been reported that the resistance used in the
Wingate anaerobic test does not elicit maximum short-
term cycling power (Dotan and Bar-Or 1983; Patton
et al. 1985). Thus, their ®ndings regarding the eects of
crank length must be interpreted cautiously. Yoshihuku
and Herzog (1990, 1996) modeled mathematically the
eects of crank length on maximal power, optimal
pedaling rate, and optimal pedal speed. They reported
that maximum power varied by 0±10% for crank
lengths of 130±210 mm, depending on the de®nition of
optimal muscle length, and that optimal pedal speed
was nearly independent of crank length. Their model,
however, featured stepwise muscle activation and
relaxation and may not have been aected by reduced
muscle excitation, which normally occurs during acti-
vation and relaxation periods (Caiozzo and Baldwin
1997; Martin et al. 2000). More recently, Martin et al.
(2000) reported that impulse and power were similar for
crank lengths of 145±220 mm, but did not report values
for maximum power, optimal pedaling rate, or optimal
pedal speed. Thus, it seems that the exact eects of
crank length on maximum power, optimal pedaling rate,
and optimal pedal speed remain to be determined.
Therefore, the purposes of this investigation were to
determine the eects of crank length on the maximum
cycling power, optimal pedaling rate, and optimal pedal
Eur J Appl Physiol (2001) 84: 413±418
DOI 10.1007/s004210100400
J.C. Martin (&)
The University of Utah, Department of Exercise
and Sport Science, 250S. 1850E. Rm. 200, Salt Lake City,
UT 84112-0920, USA
E-mail: jim.martin@health.utah.edu
Tel.: +1-801-5877704
Fax: +1-801-5853992
J.C. Martin áW.W. Spirduso
The University of Texas at Austin, Department of Kinesiology
and Health Education, Austin, TX 78712, USA
speed of human subjects, and to determine the optimal
crank length for maximum power production.
Methods
Trained male cyclists [n=16, mean (SD) age: 29 (7) years, height:
179 (6) cm, mass: 73 (7) kg] volunteered to participate in this in-
vestigation. The procedures were explained and the subjects pro-
vided written informed consent to participate. This investigation
was approved by the Institutional Review Board at The University
of Texas at Austin.
Maximal cycling was performed using crank lengths of 120,
145, 170, 195, and 220 mm. Familiarization trials were performed
with all crank lengths during the week prior to data collection. On
each experimental data collection day, subjects performed a 5-min
warm-up of steady-state cycling at 100 W, and four maximal cy-
cling power tests at one crank length. A randomized counterbal-
anced design with four ordering sequences was used for the
presentation of the crank lengths to eliminate any presentation-
order eect.
Maximal cycling power was measured using the inertial load
method (Martin et al. 1997), which determines the torque and
power delivered to an ergometer ¯ywheel across a range of pedaling
rates. The ergometer was ®tted with bicycle-racing handlebars,
cranks, pedals, and seat, and was ®xed to the ¯oor. Each subject
wore cycling shoes ®tted with a cleat that locked into a spring-
loaded binding on the pedal.
A slotted disc was mounted on the ¯ywheel and an infra-red
photodiode and detector were mounted on the ergometer frame on
opposite sides of the disc. The slots were spaced at p/8 radians (Dh)
along the perimeter of the disc, and they alternately passed or in-
terrupted the infra-red light beam. The detector circuit was pro-
grammed to emit a square pulse at each interrupt. The time between
consecutive interrupts (Dt) was recorded by a dedicated micropro-
cessor with a clock accuracy of 0.5 ls. Flywheel angular velocity
was calculated as Dh/Dt. The time-angular velocity data were low-
pass ®ltered at 8 Hz using a ®fth-order spline (Woltring 1986).
Power for each revolution of the pedal cranks was calculated as the
rate of change in ¯ywheel kinetic energy for each complete revolu-
tion of the cranks (beginning with either leg). Maximum power was
identi®ed as the highest power for a complete revolution within each
bout (i.e., the apex of the power-pedaling rate curve). Pedaling rate,
in revolutions per minute (rpm), was calculated as the reciprocal of
the time (min) required to complete each revolution of the pedal
cranks. Pedal speed (PS; m/s) was calculated from pedaling rate
(PR; rpm) and crank length (CL; m) as: PS 2pPR CL=60.
Optimal pedaling rate and optimal pedal speed were de®ned as
those values at which maximum power occurred.
In the present investigation, speci®c changes were made to the
original protocol of Martin et al. (1997), including the length of the
crank, the inertial load (IL 0:5IGR2: where IL is the iner-
tial load, I is the moment of inertia of the ¯ywheel, and GR is the
gear ratio), and the number of crank revolutions. The inertial load
was varied by adjusting the gear ratio so that the inertial resistance
at the pedal (IRPIL=CL) was similar for all crank lengths
(Table 1). The inertial loads used in this investigation do not cor-
respond to outdoor cycling; rather, they were chosen speci®cally to
elicit maximum power during our power test. The number of crank
revolutions performed in each test was varied to match the total
work across all of the crank lengths (e.g., 6.5 revolutions for the
220-mm cranks; 9.0 revolutions for the 120-mm cranks). This ap-
proach allowed the subjects to reach optimal pedaling frequency
within approximately 2 s, and to complete the test in approximately
3±4 s. Seat height was set to match each subject's accustomed riding
position and was adjusted so that the distance from the top of the
saddle to the pedal axle (in its most extended position) was constant
for all crank lengths.
Leg length, femur length, and tibia length were recorded using a
®berglass measuring tape and an anthropometer. Leg length was
de®ned as the dierence between standing height and seated height.
Femur length was de®ned as the length from the greater trochanter
to the cleft of the knee joint. Tibia length was de®ned as the length
from the cleft of the knee to the lateral maleolus.
Repeated measures analysis of variance was used to determine
whether crank length signi®cantly aected maximum cycling
power, optimal pedaling rate, or optimal pedal speed. If signi®cant
(P<0.05) main eects of crank length were detected, the Bonferoni
post hoc procedure was used to determine which crank lengths
diered. Second-order polynomial regression analysis was per-
formed to determine the optimal crank length (as a ratio of leg
length, femur length, and tibia length) for maximum power. For
that regression analysis, maximum power for each test was scaled
as a proportion of that subject's maximum value for any crank
length. Data are presented as the mean (SEM), unless stated
otherwise.
Results
The maximum power of our subjects varied by 4%
across the range of crank lengths tested, from 1149
(44) W for the 220-mm cranks to 1194 (47) W for the
145-mm cranks (Fig. 1). Maximum power produced
when using the 145- and 170-mm cranks was signi®-
cantly greater (P<0.05) than that produced with the
120- and 220-mm cranks. Optimal pedaling rate de-
creased signi®cantly (P<0.05) with increasing crank
length (Fig. 2) from 136 (3) rpm for the 120-mm cranks
to 110 (3) rpm for the 220-mm cranks. The optimal
pedaling rate for the 195-mm cranks did not dier from
that of the 170- or 220-mm cranks, but the values for all
other lengths diered. Optimal pedal speed increased
signi®cantly (P<0.05) with increasing crank length,
Table 1 Ergometer settings for the ®ve crank lengths tested
Length Gear ratio Inertial load
(kgám
2
)
a
Pedal inertial
resistance (kgám)
120 mm 5.77:1 6.45 53.8
145 mm 6.38:1 7.88 54.4
170 mm 6.98:1 9.46 55.6
195 mm 7.59:1 11.2 57.3
220 mm 7.89:1 12.1 54.9
a
The inertial resistance at the pedal for the various crank lengths
do not match exactly because of the constraint of using bicycle
chain rings and cogs with integer numbers of teeth
Fig. 1 Maximum power. Power varied by 4%, and power
produced at the 145- and 170-mm cranks was greater than that
produced at the 120- and 220-mm cranks (*P<0.05)
414
from 1.71 m/s for the 120-mm cranks to 2.53 m/s for the
220-mm cranks; the value for each crank diered from
all others (Fig. 2).
Signi®cant second-order polynomial relationships
(P<0.001) were observed between power and crank
length relative to leg length [84 (4) cm], femur length [45
(2) cm], and tibia length [41 (3) cm]. The crank length to
leg length (Fig. 3) and crank length to tibia length ratios
accounted for 20.5% and 21.1% of the variability in
maximum power, respectively, whereas the crank length
to femur length ratio accounted for only 7.1% of the
variability. The optimal crank length for maximum
power was 20% of leg length or 41% of tibia length.
Discussion
The main ®ndings of this investigation were: (1) cycle
crank lengths that varied by 83% elicited a mere 4%
variation in maximum cycling power, (2) optimal ped-
aling rate decreased with increasing crank length,
whereas optimal pedal speed increased with increasing
crank length, and (3) the optimal crank length for
maximum power was 20% of leg length or 41% of tibia
length. The variation in maximum power was only half
as large as the 8% reported by Inbar et al. (1983), and
was within the range predicted by the mathematical
models of Yoshihuku and Herzog (1990, 1996). Part of
the dierence between the 4% variation in maximum
power in the present investigation and the 8% variation
in peak power reported by Inbar et al. (1983) may be due
to dierences in measurement techniques. As mentioned
earlier, it has been shown that the Wingate anaerobic
test does not elicit maximum power (Dotan and Bar-Or
1983; Patton et al. 1985). Rather, the standard Wingate
anaerobic test resistance (75 g/kg) allows subjects to
reach pedaling rates that are on the descending limb of
the power/pedaling rate relationship, where small dif-
ferences in pedaling rate may have a large eect on
power. In contrast, in the present investigation, the in-
ertial load method was used to determine the apex of the
power/pedaling rate relationship, and thus, our values
truly represent maximum cycling power for each crank
length. In addition, Inbar et al. (1983) used a single re-
sistance for the various crank lengths tested and thus
varied the resistance at the pedal. For example, a
Monark ergometer, with a resistive load of 5.25 kg (i.e.,
a load of 0.075 kg/kg body mass for a 70-kg subject) will
produce a resistive force of 289 N at the pedal for 170-
mm cranks, 410 N for 120-mm cranks, and 224 N for
220-mm cranks. Thus, by using a constant ¯ywheel re-
sistance for various crank lengths, Inbar et al. (1983)
altered dramatically the resistive force at the pedal. Our
solution to this interaction between crank length and
pedal force was to equate the ``inertial resistance at the
pedal'' (i.e., inertial load divided by the crank length) for
the various crank lengths tested. Thus, our methods
varied the resistive torque in order to hold constant the
resistive force at the pedal.
The model of Yoshihuku and Herzog (1990, 1996)
predicted that crank lengths ranging from 130 to 210 mm
would elicit 0±10% variation in maximum power, de-
pending on the de®nition of optimal muscle length.
When optimal muscle length was de®ned as the average
of each whole muscle's length during the cycle
(Yoshihuku and Herzog 1990, 1996: model 1), predicted
power varied by less than 1%. When optimal ®ber
length was based on the cross-bridge theory (Yoshihuku
and Herzog 1996: models 2a and 2b), power varied by
approximately 10%. The 4% variation observed in the
present data falls within the predictions of those two
models, and the power produced by our subjects (1149±
1194 W) was similar to the power predicted by the model
(922±1284 W for two legs).
Our results demonstrate that optimal pedaling rate
decreases with increasing crank length, whereas optimal
pedal speed increases with increasing crank length
(Fig. 2). Even though both of these variables are rate
Fig. 3 Maximum power versus leg length to crank length ratio.
The relationship of maximum power (expressed as a percent of
each subjects best performance) with the crank length to leg length
ratio (CL/LL) was parabolic, and the regression equation was:
proportion of maximum power = )6.83(CL/LL)2+ 2.77CL/LL
0:698; P<0.001, R
2
=0.205, SE=2.4%. The optimal crank length
was 20% of leg length
Fig. 2 Optimal pedaling rate and optimal pedal speed. Optimal
pedaling rate (j) decreased with increasing crank length (*diers
from all other crank lengths; **diers from all lengths except
195 mm; ***diers from the 120- and 145-mm crank lengths).
Optimal pedal speed (p) increased with increasing crank length and
the values for all cranks diered (*)
415
terms, they may represent distinct physiological phe-
nomena. Speci®cally, pedal speed constrains the short-
ening velocity of uniarticular muscles (Martin et al.
2000; Yoshihuku and Herzog 1990), whereas pedaling
rate aects muscle excitation (Caiozzo and Baldwin
1997; Martin et al. 2000). Caiozzo and Baldwin (1997)
reported that the incomplete excitation associated with
activation and relaxation kinetics reduced force output,
and that those kinetics exerted increasingly greater eect
at higher frequency. Consequently, average excitation
for a complete cycle was reduced with increasing fre-
quency. Thus, our data suggest that the optimal condi-
tions for maximum cycling power interactively depend
upon crank length, muscle shortening velocity (con-
strained by pedal speed), and muscle excitation state
(in¯uenced by cycle frequency).
The interactive eects of crank length on optimal
pedaling rate and pedal speed also extend to the entire
power/velocity relationship. Speci®cally, the power/
pedaling rate relationships for all ®ve crank lengths
(Fig. 4A) were similar in shape, but the relationships for
the shorter cranks were shifted to the right (higher
pedaling rate). The power/pedal speed relationships
were also similar in shape (Fig. 4B), but the relationships
for the longer cranks were shifted to the right (higher
pedal speed). The combined eects of pedaling rate and
pedal speed can be accounted for by using the product of
the two as an expression of ``cyclic velocity'' (Martin
et al. 2000). When power was plotted against cyclic
velocity, the relationships for all ®ve cranks tended to
become aligned (Fig. 4C), suggesting that pedal speed
(muscle shortening velocity) and pedaling rate (muscle
excitation state) interactively constrain muscular power
across a wide range of pedaling rates and pedal speeds.
Our results for optimal pedaling rate and optimal
pedal speed contrast with those predicted by Yoshihuku
and Herzog (1990, 1996). Their model predicted that
optimal pedal speed would be nearly constant for crank
lengths of 130±210 mm (2.5±2.8 m/s), but that optimal
pedaling rate would vary by over 100% (110±232 rpm).
As mentioned previously, their model featured stepwise
activation and deactivation and therefore was not sen-
sitive to the reduced muscle excitation associated with
increasing pedaling rate. Yoshihuku and Herzog (1990)
acknowledged that particular limitation of their model,
but suggested that it would mainly aect power at very
high pedaling rates. Our results suggest that the eect of
pedaling rate on muscle excitation is more pervasive and
aects power across a wide range of pedaling rates.
The selection of optimal cycle crank length for max-
imal power production may be of interest to competitive
cyclists and to researchers who use cycle ergometry as a
laboratory-based performance measure. Our data dem-
onstrate that the optimal crank length for maximal
power was 20% of leg length or 41% of tibia length. For
our subjects, the mean optimal crank length calculated
as a proportion of leg length [169 (2) mm] was similar to
that calculated as a proportion of tibia length [170
(3) mm]. Both of these are quite similar to the standard
length of bicycle and ergometer cranks (170 mm). Op-
timal crank length (i.e., 20% of leg length) varied from
151 mm for our shortest-legged (75.7 cm leg length)
subject to 183 mm for our longest-legged subject (91.4 cm
Fig. 4A±C Power/pedaling rate and power/pedaling speed rela-
tionships. The power/pedaling rate relationships (A) for all crank
lengths (j120 mm, p145 mm, u170 mm, )195 mm, m220 mm)
were similar in shape, but the relationships for the shorter cranks
were shifted to the right (i.e., toward a higher pedaling rate). The
power/pedal speed relationships were also similar in shape (B), but
the relationships for the longer cranks were shifted to the right (i.e.,
toward a higher pedal speed). When power was plotted against the
product of pedaling rate and pedal speed (``cyclic velocity'',
expressed as Hz ´m/s; C), the relationships for all ®ve cranks
tended to converge onto one curve
416
leg length). Even though the range in optimal crank
length of our subjects was 32 mm, the regression equa-
tion (Fig. 3) indicated that standard (170 mm) length
cranks would reduce power by less than 0.5%. Thus,
standard laboratory or bicycle equipment should not
substantially compromise maximum power for most
adults.
The optimal length determined from this investiga-
tion agrees well with that reported by Inbar et al. (1983:
166 mm). Indeed, even though the methods employed by
Inbar et al. (1983) were quite dierent from those used in
the present study, the results are qualitatively similar. A
seemingly major dierence, however, is the reported
correlation of maximum power with the leg length to
crank length ratio. Inbar et al. (1983) reported a corre-
lation coecient of 0.99, whereas our value was 0.45.
That dierence is due, at least in part, to the fact that
Inbar et al. performed regression on the mean values for
each crank length, whereas values for all 16 subjects
were included in our regression model. Indeed, when
similarly analyzed, the present data yield a correlation
coecient of 0.94. This dierence in analytical tech-
niques has important implications. The analysis report-
ed by Inbar et al. (1983) suggests that the crank length to
leg length ratio accounted for approximately 98% of the
variation in peak power, and that selection of optimal
crank length is essential for maximum power produc-
tion. Conversely, our analysis suggests that the same
ratio accounted for only 20.5% of the variation in
maximum power. Thus, even though our maximum
power values were highly reproducible [coecient of
variation = 1.8 (0.2)%], the crank length to leg length
ratio accounted for only one-®fth of the total variation.
This suggests that the selection of crank length will have
only a minor impact on maximal power production.
In most of the models presented by Yoshihuku and
Herzog (1990, 1996), the highest power was predicted for
the 130-mm crank, suggesting that their model may have
been more sensitive to muscle force/length characteristics
than our human subjects. That is, predicted power was
reduced by crank lengths that elicited muscle excursion
beyond the optimal portion of the force/length rela-
tionship. Their model included force/length eects based
on the model of Woittiez et al. (Woittiez et al. 1984). For
cycling, however, the muscles undergo cyclic length
changes and are stretched prior to each contraction.
Data reported by Neptune et al. (Neptune and Herzog
2000) suggest that some portion of that stretch may occur
after muscle activation. Speci®cally, they reported that
muscle electromyographic burst onset for the gluteus
maximus occurred as early as 54°before the top dead
center of the cranks (i.e., during the leg ¯exion phase)
when subjects pedaled at 120 rpm. The observation that
muscles that act to extend the leg are activated during
leg ¯exion suggest that they are subjected to active
stretch. Muscle force/length characteristics for cycling
may, therefore, be aected by stretch-enhanced force
production, which dramatically aects the force/length
characteristics. Speci®cally, Edman et al. (1978) reported
that muscle force was nearly constant from resting length
to 25% above resting length following stretch, whereas
force was reduced by approximately 15% over that same
range without stretch. In addition, Stevens (1993)
reported that muscles produced more force when per-
forming work-loops (activated 54°before shortening)
than when performing traditional force/velocity mea-
surements at the same velocity. Taken together, these
investigations provide compelling support for the notion
that stretch-enhanced force production aects muscular
power during cycling. Thus, stretch-enhanced force
production may account for at least some of the dier-
ences between our human data and the values predicted
by the model of Yoshihuku and Herzog (1990, 1996).
A potential limitation inherent in our methods was
that, by changing the inertial load in concert with crank
length, we may have in¯uenced the measurement of
maximum power, optimal pedaling rate, or optimal
pedal speed. However, the inertial load method used in
this investigation relies solely on the reaction torque of
the ¯ywheel to provide resistance. Thus, at any pedaling
rate, the measured power is exactly what the subject
produced, regardless of the inertial load. In addition,
extensive pilot testing in our laboratory has revealed
that both the maximum power and optimal pedaling
rate for 170-mm cranks were stable across a wide range
of inertial load conditions. Consequently, we are con®-
dent that the methods used in this investigation allowed
us to determine accurately maximum power, optimal
pedaling rate, and optimal pedal speed for each crank
length. Finally, the inertial loads used in this investiga-
tion were substantially lower than those experienced by
a cyclist using a racing gear ratio and, thus, might not
apply to road or track cycling. However, Fregly et al.
(1996) reported that inertial load has little eect on
pedaling coordination, suggesting that our ergometer
results are indeed applicable to outdoor cycling, even
though the inertial characteristics dier.
In summary, cycle crank lengths that varied by 83%
elicited a mere 4% variation in maximum cycling power.
Optimal pedaling rate decreased with increasing crank
length, whereas optimal pedal speed increased with in-
creasing crank length. The diering optimal conditions
for these two rate terms suggest that pedal speed (which
represents muscle shortening velocity) and pedaling rate
(which in¯uences muscle excitation) exert distinct eects
that limit muscular power during cycling. The optimal
crank length for maximal power was 20% of leg length
[169 (2) mm] or 41% of tibia length [170 (3) mm]. Even
though our results reveal an optimal crank length, it
must be recognized that the crank length to leg length
and crank length to tibia length ratios accounted for
only 20.5% and 21.1% of the variability in maximum
power exhibited by our subjects. Indeed, the use of
170-mm cranks would only reduce the power of our
shortest- and longest-legged subjects by less than 0.5%,
suggesting that standard laboratory or bicycle equip-
ment should not substantially compromise maximum
power for most adults.
417
Acknowledgements The authors wish to extend their sincere ap-
preciation to the participants in this study for their enthusiasm.
Experiments conducted in this investigation comply with current
laws in the United States of America.
References
Caiozzo VJ, Baldwin KM (1997) Determinants of work produced
by skeletal muscle: potential limitations of activation and re-
laxation. Am J Physiol 273:C1049±1056
Dotan R, Bar-Or O (1983) Load optimization for the Wingate
anaerobic test. Eur J Appl Physiol 51:409±417
Edman KA, Elzinga G, Noble MI (1978) Enhancement of me-
chanical performance by stretch during tetanic contractions of
vertebrate skeletal muscle ®bres. J Physiol (Lond) 281:139±155
Fregly BJ, Zajac FE, Dairaghi CA (1996) Crank inertial load has
little eect on steady-state pedaling coordination. J Biomech
29:1559±1567
Inbar O, Dotan R, Trousil T, Dvir Z (1983) The eect of bicycle
crank-length variation upon power performance. Ergonomics
26:1139±1146
Martin JC, Wagner BM, Coyle EF (1997) Inertial-load method
determines maximal cycling power in a single exercise bout.
Med Sci Sports Exerc 29:1505±1512
Martin JC, Brown NA, Anderson FC, Spirduso WW (2000) A
governing relationship for repetitive muscular contraction.
J Biomech 33:969±974
Neptune RR, Herzog W (2000) Adaptation of muscle coordination
to altered task mechanics during steady-state cycling. J Biomech
33:165±172
Patton JF, Murphy MM, Frederick FA (1985) Maximal power
outputs during the Wingate anaerobic test. Int J Sports Med
6:82±85
Stevens ED (1993) Relation between work and power calculated
from force-velocity curves to that done during oscillatory work.
J Muscle Res Cell Motil 14:518±526
Too D, Landwer GE (2000) The eect of pedal crank arm length
on joint angle and power production in upright cycle ergome-
try. J Sports Sci 18:153±161
Woittiez RD, Huijing PA, Boom HB, Rozendal RH (1984) A
three-dimensional muscle model: a quanti®ed relation between
form and function of skeletal muscles. J Morphol 182:95±113
Woltring HJ (1986) A FORTRAN package for generalized, cross-
validatory spline smoothing and dierentiation. Adv Eng Soft
8:104±113
Yoshihuku Y, Herzog W (1990) Optimal design parameters of the
bicycle-rider system for maximal muscle power output.
J Biomech 23:1069±1079
Yoshihuku Y, Herzog W (1996) Maximal muscle power output in
cycling: a modelling approach. J Sports Sci 14:139±157
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... Previous researchers have reported changing of CAL affect cycling power production (MacDermid & Edwards, 2010;Martin & Spirduso, 2001;Too & Landwer, 2000), lower limb joint angle, cadence (Barratt et al., 2011(Barratt et al., & 2016Candotti et al., 2007;Christiansen et al., 2013), pedal torque (Hull & Gonzalez, 1988), lower limb muscle activity (Watanabe, 2020), and VȮ2 (Ferrer-Roca et al., 2017;Morris & Londeree, 1997). ...
... The effect of different CALs on cycling power, lower extremity joint kinematics, and kinetics during such a short duration (~30 seconds) with supramaximal effort have been well documented (Barratt et al., 2011;Christiansen et al., 2013;MacDermid & Edwards, 2010;Martin & Spirduso, 2001;Too & Landwer, 2000;Watanabe, 2020). There is also a strong body of research that provides insight into the physiological and biomechanical ...
... However, other studies have been reported that there were no significant differences in cycling power, joint angle, and VȮ2 depends on when using different CALs (Barratt et al., 2011;Inbar et al., 1983;MacDermid & Edwards, 2010;McDaniel et al., 2002;Morris & Londeree, 1997;Watanabe, 2020). Furthermore, previous studies were limited in the type of subject recruited either elite or well-trained cyclists (Barratt et al., 2011(Barratt et al., & 2016Christiansen et al., 2013;Korff et al., 2007;MacDermid & Edwards, 2010;Martin & Spirduso, 2001;McDaniel et al., 2002;Morris & Londeree, 1997) or young healthy students (Ferrer-Roca et al., 2017;Hull & Gonzalez, 1988;Inbar et al., 1983;Too & Landwer, 2000;Watanabe, 2020). ...
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Given the nature of a triathlon race, the cycling distance is typically much longer than swimming and running across race distances from sprint to Ironman. Besides, triathletes should try to not only maintain a certain level of cycling power but also consider cycling economy to make a better performance in both the cycling portion and the overall race (Bonacci et al., 2013; Sleivert & Rowland, 1996; Swinnen et al., 2018). The cycling economy is an important indicator to predict cycling performance in terms of time to complete a certain distance. Both cycling economy and performance are determined by the interaction between mechanical output and physiological input (Barratt et al., 2016; Korff et al., 2007; Sunde et al., 2010). Theoretically, improving cycling economy elicits a better cycling time trial performance and/or less physiological demands (e.g., rate of oxygen consumption: V̇O2, heart rate) to complete at a given distance. The crank arm length (CAL) is one of the important factors among many variables that affect the economy and performance in cycling (McDaniel et al., 2002). Therefore, the appropriate selection of CAL may play a key role in improving the cycling portion of the race and entire triathlon performance. The purpose of this review is to identify the effects of acute changing CAL on physiological and biomechanical responses during cycling.
... This proposition is supported by the finding that pedal and joint-specific power production does not meaningfully change across a broad range (e.g. 145 to 195mm) of crank lengths [65,66]. Force-velocity and activation-relaxation requirements placed on muscle are linearly coupled for a given crank length during cycling [58,66,67], and therefore maximal muscle power production during sprint cycling (i.e. for a given individual) is determined primarily by pedalling rate. ...
... 145 to 195mm) of crank lengths [65,66]. Force-velocity and activation-relaxation requirements placed on muscle are linearly coupled for a given crank length during cycling [58,66,67], and therefore maximal muscle power production during sprint cycling (i.e. for a given individual) is determined primarily by pedalling rate. ...
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Maximal muscular power production is of fundamental importance to human functional capacity and feats of performance. Here, we present a synthesis of literature pertaining to physiological systems that limit maximal muscular power during cyclic actions characteristic of locomotor behaviours, and how they adapt to training. Maximal, cyclic muscular power is known to be the main determinant of sprint cycling performance, and therefore we present this synthesis in the context of sprint cycling. Cyclical power is interactively constrained by force-velocity properties (i.e. maximum force and maximum shortening velocity), activation-relaxation kinetics and muscle coordination across the continuum of cycle frequencies, with the relative influence of each factor being frequency dependent. Muscle cross-sectional area and fibre composition appear to be the most prominent properties influencing maximal muscular power and the power-frequency relationship. Due to the role of muscle fibre composition in determining maximum shortening velocity and activation-relaxation kinetics, it remains unclear how improvable these properties are with training. Increases in maximal muscular power may therefore arise primarily from improvements in maximum force production and neuromuscular coordination via appropriate training. Because maximal efforts may need to be sustained for~15-60 s within sprint cycling competition, the ability to attenuate fatigue-related power loss is also critical to performance. Within this context, the fatigued state is characterised by impairments in force-velocity properties and activation-relaxation kinetics. A suppression and leftward shift of the power-frequency relationship is subsequently observed. It is not clear if rates of power loss can be improved with training, even in the presence adaptations associated with fatigue-resistance. Increasing maximum power may be most efficacious for improving sustained power during brief maximal efforts, although the inclusion of sprint interval training likely remains beneficial. Therefore, evidence from sprint cycling indicates that brief maximal muscular power production under cyclical conditions can be readily improved via appropriate training, with direct implications for sprint cycling as well as other athletic and health-related pursuits. Maximal muscle power production under cyclical conditions is interactively constrained by force-velocity properties, activation-relaxation kinetics and muscle coordination across the continuum of possible movement frequencies. Fatigue alters the power-frequency relationship, with a higher degree of power loss at higher movement frequencies. Maximal muscular power production can be readily increased with appropriate strength and power training; it remains less clear if rates of power loss during brief maximal sustained efforts can be improved with training.
... Understanding the relationship between body structures and cycling parameters (such as seat height and crank length) is not only important for patients to perform rehabilitative exercises but can also guide healthy people to perform physical activities safely. For example, setting an appropriate crank length [5][6][7], pedaling cadence [8], and the pedal condition [9,10] (pedal height and pedal position) affects the outcomes of rehabilitation. Martin and Spirduso [8] divided 710 feasible pedal places into 16 groups for modeling and simulation and found that knee joint forces were smaller near saddle position (SP). ...
... For example, setting an appropriate crank length [5][6][7], pedaling cadence [8], and the pedal condition [9,10] (pedal height and pedal position) affects the outcomes of rehabilitation. Martin and Spirduso [8] divided 710 feasible pedal places into 16 groups for modeling and simulation and found that knee joint forces were smaller near saddle position (SP). Conversely, the ankle and hip joints in the far SP per saddle height (SH) were minimal. ...
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Background: Many sports and physical activities can result in lower limb injures. Pedaling is an effective exercise for lower extremity rehabilitation, but incorrect technique may cause further damage. To some extent, previous experiments have been susceptible to bias in the sample recruited for the study. Alternatively, methods used to simulation activities can enable parametric studies without the influence of noise. In addition, models can facilitate the study of all muscles in the absence of the effects of fatigue. This study investigated the effects of crank length on muscle behavior during pedaling. Methods: Six muscles (soleus, tibialis anterior, vastus medialis, vastus lateralis, gastrocnemius, and rectus femoris), divided into three groups (ankle muscle group, knee muscle group, and biarticular muscle group), were examined under three cycling crank lengths (100 mm, 125 mm, and 150 mm) in the present study. In addition, the relationship between crank length and muscle biological force was analyzed with the AnyBody Modeling System™, a human simulation modeling software based on the Hill-type model. Findings. Based on inverse kinematic analysis, the results indicate that muscle activity and muscle force decrease in varying degrees with increases in crank length. The maximum and minimum muscular forces were attained in the tibialis anterior and vastus lateralis, respectively. Interpretation. Studying the relationship between muscle and joint behavior with crank length can help rehabilitation and treating joint disorders. This study provides the pedal length distribution areas for patients in the early stages of rehabilitation.
... The development of maximal peak power is determined by both mechanical and physiological determinants. Additionally, maximal power production is dependent on the cadence or "pedalling rate" (Martin & Spirduso, 2001). Specifically, as highlighted by Douglas et al., (Douglas, Ross, & Martin, 2021) cycling power is determined by a combination of force-velocity properties, activation-relaxation kinetics and muscle coordination, across the cadence continuum. ...
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The aim of this study was to evaluate a field-based approach to determine torque-cadence and power-cadence profiles in professional cyclists and establish if this field-based protocol can differentiate between varying rider specializations. Twenty-four male professional athletes from a World Tour cycling team participated in this investigation (Height = 1.84 ± 0.05 m, Weight = 72.3 ± 5.6 kg, Age = 25 ± 4 y). All riders were subsequently categorized into the following groups: 1) General Classification (GC) group; 2) sprinter group; and 3) classics group. All participants completed a specific sprint protocol in the field which included 6 times 6s sprints with varying gearing, starting cadences, starting speeds and position (i.e. seated vs standing). Power-cadence and torque-cadence profiles were determined based on the sprint outputs. There was a significant main effect of rider specialization on the measured (sprint) variables (P≤0.03). Body weight, maximum power outputs (1s, 10s and modelled) and maximum torque were highest in the sprinter group, followed by the classics group, followed by the GC group. The protocol was able to differentiate between different rider specializations (i.e. GC, sprinters, classics). The proposed methodology can contribute to individualizing training content in the short-duration domain.
... Similar to the BMX races (Gianikellis et al., 2011;Grigg et al., 2017;Kalichová et al., 2013), also in track cycling a basis for a quick start is a proper coordination and synchronization of the body posture with the movement of the grid (as an example in the 1-km race). The crank length (Martin & Spirduso, 2001) and its initial position/angle (Padulo et al., 2015) as well as the gear ratio (Mognoni & di Prampero, 2003) were also observed to influence starting performance. ...
Article
Purpose: In modern sprint cycling competitions, the athletes perform a preparatory movement that consists in reaching the backmost standing position, quickly accelerating the body forward at the starting signal. The purpose of this study was to investigate the kinematics of backward standing starts in elite cyclists, as well as the effect of initial crank angle. Methods: Video analysis of cycling starts was performed in seven male elite cyclists during 30 m sprints and in 3 starting conditions: seated with a self-selected crank angle (S-ss), backward standing from a self-selected (BSt-ss) or imposed crank angle of 90° (BSt-90°). Average velocity after 5 and 30 m was also measured by means of a photocell system. Results: No differences in starting crank angle were observed between BSt-ss and S-ss (about 64°). The fastest starts were attained in BSt-ss (highest velocity at 5 and 30 m); in this condition, angular downstroke velocity was the highest and the counter movement occurred earlier than in BSt-90°. Significant positive associations were observed between angular velocity in the first downstroke and forward velocity at 5 and 30 m. Conclusions: These findings indicate that backward standing starts improve cycling performance (compared to seated starts), that an initial crank angle < 90° is preferable, and that elite cyclists maintain the initial advantage at least up to a distance of 30 m.
... Vogt et al. (2006) assessed in laboratory the averaged power at 11.41m/s in six cyclists and it ranged between 190 W and 392 W. The protocol started with a resistance of 100 W and increments of 20 W each 3 min. The power output was measured in different heart rate zones and near 169 ± 7 bpm power output was 392 ± 55 W. Others assessed the influence of the cycle crank length and presented maximal power values near 1200 W (Martin & Spirduso, 2001). Even more, at 50 km/h (13.89 m/s) power values range between 864 ± 107 W and 940 ± 83 W (Wiles, Coleman, Tegerdine, & Swaine, 2006). ...
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The aim of this study was to assess and compare by numerical simulations and analytical models the resistive forces, mechanical power, energy cost and velocity using two different types of road helmets (standard vs aero road helmet). An elite cyclist was scanned on the racing bicycle, wearing his competition gear and helmets. Numerical simulations by Computational Fluid Dynamics were carried-out at 11.11 m/s (40 km/h) and 20.83 m/s (75 km/h) to extract the drag force. The mechanical power and energy cost were estimated by analytical procedures. The drag forces were between 9.93 N and 66.96 N across the selected speeds and helmets. The power to overcome drag were 182.19 W and 1121.40 W. The total power lower and higher values were 271.05 W and 1558.02 W. The energy cost estimation was between 106.89 J/m and 381.40 J/m across the different speeds and helmets. The standard helmet imposed higher drag and demanded more power.
... Cardiorespiratory fitness was determined using an incremental cycle ergometry test (Ergoline GmbH, Germany) and indirect calorimetry using the portable K5 system (COS-MED, Italy) under the supervision of a certified exercise physiologist (SE). Cycle crank length for each participant was adjusted following methods by Martin and Spirduso [29]. The K5 has been shown to be valid and reliable for metabolic measurements [30]. ...
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Objective Secondary consequences of juvenile idiopathic arthritis (JIA) may impact long-term health outcomes. This study examined differences in physical activity, cardiorespiratory fitness, adiposity, and functional performance in children and adolescents with JIA compared to their typically developing (TD) peers.Methods Participants with JIA (n = 32; 10–20 years old) and their TD peers (n = 35) volunteered for assessments of: daily moderate-to-vigorous physical activity (MVPA, body-worn accelerometer); peak oxygen consumption (VO2 Peak, incremental bike test); fat mass index (FMI, dual-energy X-ray absorptiometry); and triple-single-leg-hop (TSLH) distance. Statistical analyses were performed in R using four linear mixed-effect models with Bonferroni adjustment (⍺ = 0.0125). Fixed effects were group, sex, and age. Participant clusters based on sex and age (within 1.5 years) were considered as random effects.ResultsParticipants with JIA displayed lower mean daily MVPA than their TD peers [p = 0.006; β (98.75% CI); −21.2 (−40.4 to −2.9) min]. VO2 Peak [p = 0.019; −1.4 (−2.5 to −0.2) ml/kg/min] decreased with age. Females tended to have lower VO2 Peak [p = 0.045; −6.4 (−13.0 to 0.4) ml/kg/min] and greater adiposity [p = 0.071; 1.4 (−0.1 to 3.0) kg/m2] than males.Conclusion The findings support the need for strategies to promote MVPA participation in children and adolescents with JIA. Sex and age should be considered in research on the consequences of JIA.
... Recientes estudios han abordado la problemática del correcto ajuste de la biela, ya que, en esencia, contribuye a la altura efectiva del sillín. Así, para el ciclismo de carretera, se recomienda utilizar una longitud de biela entre el 20-21% de la diferencia entre la talla y la talla sentado (Martin & Spirduso, 2001), lo que viene a ser similar a un 20% de la altura de la entrepierna (Belluye & Cid, 2001). Asumiendo que la altura de la entrepierna representa aproximadamente un 47-49% de la estatura (Ferrer-Roca et al., 2012;, una referencia más genérica podría ser que ciclistas de estatura inferior a 160, 170 y 180 cm deberían utilizar bielas de 160, 165 y 170 mm, siendo las bielas de 172.5 y 175 mm recomendables para ciclistas de más de 180 y 185 cm, respectivamente. ...
Article
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Llevar una postura correcta sobre la bicicleta durante la práctica de ciclismo de carretera es muy importante para prevenir lesiones y mejorar el confort, el rendimiento y la seguridad. Una revisión de la literatura revela que un gran porcentaje de ciclistas sufre molestias ocasionadas por un incorrecto ajuste de la bicicleta o tipo de sillín utilizado. Entre las más comunes caben mencionarse el entumecimiento en la zona perineal, la excoriación o la hematuria. Específicamente en mujeres se ha detectado que tanto los diferentes modelos como los métodos de ajuste del sillín utilizados no son verdaderamente útiles, siendo las molestias en la zona perineal más frecuentes que en hombres. A la vista de estos problemas, en los últimos años se han desarrollado modelos de sillín específicos para mujer. Sin embargo, sólo unos pocos estudios han analizado el efecto de éstos sobre el confort en las mujeres durante el pedaleo.
Article
This study investigated the effect of crank length on biomechanical parameters and muscle activity during standing cycling. Ten participants performed submaximal cycling trials on a stand-up bicycle using four crank lengths. Joint angles, moments, powers, and works of the lower limbs were calculated from motion data and pedal reaction forces. Electromyographic (EMG) data were recorded from gluteus maximus (GM), vastus medialis, rectus femoris, biceps femoris (BF), gastrocnemius medialis, soleus, and tibialis anterior, and used to obtain the integrated EMG. Statistical parametric mapping was employed to analyse the biomechanical parameters throughout the pedalling cycle. Knee and hip flexion angles and hip power increased at the initiation (0–20%) of pedalling with increasing crank length, while the BF and GM muscle activities increased during propulsion (20–40%). Additionally, increasing the crank length resulted in increased knee power absorption during upstroke phase (70–100%). Peak knee extension moment increased with decreasing crank length during propulsion, but the moment at a short crank length during propulsion was comparable to fast walking. Consequently, longer crank lengths require increased propulsion power by the lower limb muscles during standing cycling compared to shorter crank lengths. Therefore, shorter crank lengths are recommended for stand-up bicycles to avoid fatigue.
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The purpose of the present study was to define the optimal bicycle crank length (CL) for eliciting maximal leg power output during a 30 s power test (Wingate Anaerobic Test). Thirteen male students 22-27 years old served as subjects for this study. In each of the five sessions the test was administered on a mechanically braked cycle-ergometer modified by a crank slider-assembly which permitted continuous crank-length adjustment. Five evenly spaced CLs, centred around the conventional 17.5 cm crank, ranging from 12.5 to 22.5 cm, were used. The measured variables were mean (MP) and peak (PP) power output. A parabola-fitting technique was employed to define the optimal CL from the MP and PP data. The resulting optimal CL was 16.4 and 16.6 cm for MP and PP, respectively. Optimal CL was shown to depend on leg length. However, within a two crank length span (± 5 cm) about the optimal crank length MP and PP did not vary by more than 0.77 and 1.24% respectively. It is suggested that for a homogenous population, such as used in this study, the conventional 17.5 cm crank is close to the calculated optimum for power production. However, a failure to adjust this factor to the anthropometric dimensions of populations, heterogenous in size, may result in a much greater fall-off in cycle short-term power performance.
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The purpose of the present study was to define the optimal loads (OL) for eliciting maximal power-outputs (PO) in the leg and arm modes of the 30s Wingate Anaerobic Test (WAnT). Eighteen female and seventeen male physical education students, respectively 20.6 +/- 1.6 and 24.1 +/- 2.5 years old, volunteered to participate. In each of the total five sessions, the test was administered twice on a convertible, mechanically braked cycle-ergometer, once for the legs and once for the arms. The five randomized, evenly-spaced resistance loads ranged from 2.43 to 5.39 Joule per pedal revolution per kg body weight (B. W.) for the legs, and from 1.96 to 3.92 for the arms. The measured variables were mean (MP x kg-1) and peak PO as well as absolute and relative measures of fatigue. A parabola-fitting technique was employed to define the optimal loads from the MP x kg-1 data. The resulting OL were 5.04 and 5.13 Joule x Rev-1 x kg B.W.-1 in the leg and 2.82 and 3.52 in the arm tests for the women and men, respectively. OL were shown to depend on PO magnitude. However, within a two-load span (0.98 Joule x Rev-1 x kg B.W.-1) about the OL, MP x kg-1 did not vary by more than 1.4% in the leg and 2.2% in the arm tests. It is suggested that although the WAnT is rather insensitive to moderate variation in load assignment, improved results could be obtained by using the stated OL as guidelines that may be modified according to individual body build, composition, and, particularly, anaerobic fitness level.
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Based on the spline software of Lyche et al., a subroutine package is presented in which the amount of smoothing on a set of n noisy datapoints is determined from the data by means of the Generalized Cross-Validation (GCV) or predicted Mean-Squared Error (MSE) criteria of Wahba and her collaborators. Following an idea of Hutchinson and de Hoog, an efficient O (m2n) algorithm is used for calculating the criterion functions, where 2m is the order of the spline function. In this fashion, earlier O (n3) approaches based on the singular value decomposition can be avoided.
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Single fibres from the semitendinosus muscle of Rana temporaria were stretched during fused tetanic contractions and tension and sarcomere length (laser diffraction) responses were recorded. Stretch to the fibres caused proportional increase in length of the sarcomeres. The force increased to a plateau value which was maintained during stretch or increased slightly. The plateau value of force during stretch was dependent upon the velocity of stretch, was independent of the amplitude of stretch and was not proportional to overlap of thick and thin filaments. There was enhancement of force after stretch compared with that produced at the same sarcomere length during isometric tetani. This force enhancement was independent of the velocity at which the stretch had been applied. At sarcomere lengths between 1.9 and 2.3 μm, the force enhancement after stretch decayed rapidly, was independent of amplitude of stretch above approximately 25 nm per sarcomere and was not associated with a shift of the force-velocity curve. At sarcomere lengths above 2.3 μm the force enhancement after stretch decayed very slowly and was still present after 4 sec in long tetani. At sarcomere lengths above 2.3 μm, force enhancement after stretch increased with amplitude of stretch and increased for any given stretch amplitude with sarcomere length. The force recorded after stretch was thus not proportional to overlap of thick and thin filaments. At sarcomere lengths above 2.3 μm, the force enhancement after stretch was associated with a shift towards higher force values of the force-velocity curve. The velocity of shortening at zero load (V(max)) derived by hyperbolic extrapolation of the force-velocity curve was not affected. Tension enhancement during and after stretch has a stabilizing effect in preventing dispersion of sarcomere length, particularly on the descending limb of the length-tension curve.
Article
The purpose of this study was to find the optimal values of design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height, and rate of crank rotation) which maximize the power output from muscles of the human lower limb during bicycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four smooth pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's equation. The dependence of the average power on the design parameters was examined. The instantaneous power of each muscle group was studied and simultaneous activity of two seemingly antagonistic muscle groups was analyzed. Average peak power for one full pedal revolution was found to be around 1100 W. The upper body position corresponding to this peak power output was slightly reclined, and the pedalling rate was 155 rpm for a nominal crank length of 170 mm.
Article
The purpose of this study was to determine the resistance loads which elicit maximal values of power output (PO) during performance of the Wingate test (WT). Nineteen male subjects (mean age, 25.1 yrs; mean VO2 max, 3.52 l/min) performed multiple WTs in a random order at resistances ranging from 3.23 to 6.76 joules/pedal rev/kg BW. Tests were carried out on a Monark cycle ergometer modified to permit instantaneous application of resistance. Revolutions were determined by a computer interfaced frequency counter. The mean resistances eliciting the highest peak power (PP) and mean power (MP) outputs were 5.65 and 5.53 joules/pedal rev/kg BW, respectively (average of 5.59 joules/pedal rev/kg BW). Both PP and MP were significantly higher (15.5% and 13.0%, respectively) using a resistance load of 5.59 compared to the Wingate setting of 4.41 joules/pedal rev/kg BW. The test-retest reliability for PP and MP ranged between 0.91 and 0.93 at both resistance loads. Body weight and thigh volume did not significantly estimate the individual resistances eliciting maximal POs. The data suggest that resistance be assigned according to the subjects BW but consideration be given to increasing the resistance from that presently used in various laboratories.
Article
A three-dimensional muscle model with complex geometry is described and tested against experimental data. Using this model, several muscles were constructed. These muscles have equal optimum length but differ in architecture. The force exerted by the constructed muscles, in relation to their actual length and velocity of shortening, is discussed. Generally speaking, the constructed muscles with considerable pennation have great fiber angles, a great physiological cross section, a narrow active and steep passive length-force relation, and a low maximal velocity of shortening. The maximal power (force times velocity) delivered by the constructed muscles is shown to be almost independent of the architecture of the muscles. The steepness of the passive length-force relation is determined mainly by the shortest fibers within the group of constructed muscles, whereas maximal velocity of shortening and the width of the active length-force relation are determined mainly by the longest fibers. The validity of the three-dimensional muscle model with respect to some morphological and functional characteristics is tested. Length-force relations of constructed muscles are compared with the actual length-force relations of mm. gastrocnemii mediales and mm. semimembranosi of male Wistar rats. Moreover, actual fiber angle, fiber length, and muscle thickness of three mm. gastrocnemii mediales are compared with values found for constructed muscles. It is concluded that the three-dimensional muscle model closely approximates the actual muscle form and function.
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The force-velocity relation during oscillatory work was compared with that measured in the traditional way with quick release and force clamps using toad sartorius, frog sartorius, and mouse soleus muscles. Plotting the force and corresponding velocity data in this way produces a 'power-loop'. The 'power-loop' has less intuitive value than the frequently reported 'work-loops' but it is useful because it permits comparison with the force-velocity curve produced using traditional methods. The force/velocity combinations for oscillatory work during a contraction often exceed those that would be predicted from the force-velocity curve. Although it has been known for many years that more force is developed by stimulated muscle when it is being stretched than can be developed during an isometric contraction, my results show that the increase in force is of importance at stretch velocities that probably occur in vivo during locomotion.
Article
This study sought to find the optimal design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height and rate of crank rotation) that maximise the power output from muscles of the human lower limb during cycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four frictionless pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's (1938) equation, incorporating the muscle force-length relation. The force-length relation and the values of length that served as input into the relations of the various muscles were defined in the following two ways: (1) the force-length relation was parabolic, based on the experiment of Woittiez et al. (1984), and the length was defined as the whole muscle length; and (2) the force-length relation was expressed as a combination of lines, based on the cross-bridge theory, and the length was defined as muscle fibre length. In the second definition, the joint configurations at which four of the seven muscle groups reached optimal length (i.e. the length at which the muscle can exert maximal isometric force) were further given in two ways. The first way was consistent with a previous study from this laboratory (Yoshihuku and Herzog, 1990); the second way relied on unpublished experimental data. The dependence of the average power on the design parameters and definitions of the force-length relation and muscle length was examined. Maximal average power for one full crank rotation with a crank length of 0.17 m was found to be about 1300 W for definition 1 and 1000 W for definition 2. The average power was more sensitive to changes in design parameters in definition 2 than definition 1. The optimal rate of crank rotation with a crank length of 0.17 m was 18.4 rad s-1 (176 rev min-1) for definition 1 (this value is different from the result of the previous study due to revisions in input for two muscle groups), and 15.2 rad s-1 (145 rev min-1) and 14.6 rad s-1 (139 rev min-1) for definition 2.
Article
Inertial load can affect the control of a dynamic system whenever parts of the system are accelerated or decelerated. During steady-state pedaling, because within-cycle variations in crank angular acceleration still exist, the amount of crank inertia present (which varies widely with road-riding gear ratio) may affect the within-cycle coordination of muscles. However, the effect of inertial load on steady-state pedaling coordination is almost always assumed to be negligible, since the net mechanical energy per cycle developed by muscles only depends on the constant cadence and workload. This study test the hypothesis that under steady-state conditions, the net joint torques produced by muscles at the hip, knee, and ankle are unaffected by crank inertial load. To perform the investigation, we constructed a pedaling apparatus which could emulate the low inertial load of a standard ergometer or the high inertial load of a road bicycle in high gear. Crank angle and bilateral pedal force and angle data were collected from ten subjects instructed to pedal steadily (i.e., constant speed across cycles) and smoothly (i.e., constant speed within a cycle) against both inertias at a constant workload. Virtually no statistically significant changes were found in the net hip and knee muscle joint torques calculated from an inverse dynamics analysis. Though the net ankle muscle joint torque, as well as the one- and two-legged crank torque, showed statistically significant increases at the higher inertia, the changes were small. In contrast, large statistically significant reductions were found in crank kinematic variability both within a cycle and between cycles (i.e., cadence), primarily because a larger inertial load means a slower crank dynamic response. Nonetheless, the reduction in cadence variability was somewhat attenuated by a large statistically significant increase in one-legged crank torque variability. We suggest, therefore, that muscle coordination during steady-state pedaling is largely unaffected, though less well regulated, when crank inertial load is increased.